Oil light
05-15-2004, 02:46 AM
#1
Instructor
Thread Starter
Oil light
It happened once or twice everytime I drove my 1990 C4, in past 2 or 3 weeks. 
At low speed, the oil light and "!" light came on suddenly, but oil pressure and oil level are ok. But these lights will off very soon, only stay for few seconds.
The first time happened in the traffic, very low speed, almost idle. The second and third times was when the car came to stop at traffic light, and engine was stalled at the same time (couldn't tell which came first, stall or oil light). Then it happened another few times, but both oil pressure and oil level are ok, and no engine stall.
I noticed that the oil pressure at idle is around 0.8bar, after I changed from Castro 10W-60 to Mobil 15W-50. Before I changed, it was 1 bar. But I think it may not be the reason because this problem appeared before I changed the oil.
Anyone knows what's the problem? Is it jsut the sensor or other more serious problems?
(The engine has some minor leak at right cylinder head area and crank case, is this the reason?)
Thanks!
At low speed, the oil light and "!" light came on suddenly, but oil pressure and oil level are ok. But these lights will off very soon, only stay for few seconds.
The first time happened in the traffic, very low speed, almost idle. The second and third times was when the car came to stop at traffic light, and engine was stalled at the same time (couldn't tell which came first, stall or oil light). Then it happened another few times, but both oil pressure and oil level are ok, and no engine stall.
I noticed that the oil pressure at idle is around 0.8bar, after I changed from Castro 10W-60 to Mobil 15W-50. Before I changed, it was 1 bar. But I think it may not be the reason because this problem appeared before I changed the oil.
Anyone knows what's the problem? Is it jsut the sensor or other more serious problems?
(The engine has some minor leak at right cylinder head area and crank case, is this the reason?)
Thanks!
05-15-2004, 03:13 AM
#2
Addict
Lead Rennlist
Technical Advisor
Rennlist
Lifetime Member
Lead Rennlist
Technical Advisor
Rennlist
Lifetime Member
Dear Patrick,
When the 964 stalls this means the rpm dropped too low. Why this happens is another issue.
When the rpm is too low the oil pump which is engine driven does not generate enough oil pressure and the oil pressure warn will come on before you stall. Obviously it will come on afterwards.
What is your idle speed? 0.8 bar at 800 rpm is far far too low if the oil is cold and still too low when the oil is very hot.
At this level of pressure the oil pressure warn is likely to come on if the rpm dips.
First thing you need to check is the oil contents of the engine. Do you have enough oil?
As I asked, what is the normal rpm level?
I doubt that it is the sensor problem based on your post. You have a genuine low oil pressure situation but your post does not contain certain information needed. You are using fairly thick oils as well so this is also a concern.
You may need to do a compression test on each cylinder and maybe even a leak down test.
Ciao,
Adrian
964C4
When the 964 stalls this means the rpm dropped too low. Why this happens is another issue.
When the rpm is too low the oil pump which is engine driven does not generate enough oil pressure and the oil pressure warn will come on before you stall. Obviously it will come on afterwards.
What is your idle speed? 0.8 bar at 800 rpm is far far too low if the oil is cold and still too low when the oil is very hot.
At this level of pressure the oil pressure warn is likely to come on if the rpm dips.
First thing you need to check is the oil contents of the engine. Do you have enough oil?
As I asked, what is the normal rpm level?
I doubt that it is the sensor problem based on your post. You have a genuine low oil pressure situation but your post does not contain certain information needed. You are using fairly thick oils as well so this is also a concern.
You may need to do a compression test on each cylinder and maybe even a leak down test.
Ciao,
Adrian
964C4
05-15-2004, 08:37 AM
#3
1st Gear
Join Date: Apr 2004
Location: London England
Posts: 1
Likes: 0
Received 0 Likes
on
0 Posts
My C2 Tip has recently developed this problem as well, but without the stalling - the light comes on as I come to a halt, once the car is fully warmed up (temp gauge at about 9pm). It always comes on for the same amount of time - 12 seconds - which I assume is the minimum once it's triggered. The oil pressure gauge works fine, although it does show very low pressure at idle. The idle speed with the Tip in drive is about 550 rpm. If I slip it out of drive as I come to a halt, the rpm doesn't go down to 550 and the light stays off. I'm pretty sure I have no genuine oli pressure problems - I've recently had a top end rebuild, and the car now uses virtually no oil at all. I suspect the sensor, but am not sure how difficult /expensive it is to change.
Jonathan
Jonathan
05-15-2004, 11:56 AM
#4
Instructor
Thread Starter
Adrian,
My idle rpm is slightly above the third line of tachometer (the line below "1"), and I assume it's around 700~800rpm. The oil pressure is slightly below the "1" when engine is hot (temp gage above 8 o'clock line).
Most of the time idle and oil pressure are pretty stable, but sometimes they will drop a little bit then come back again. At full throttle, oil pressure will go up to around 5, but not over 5. (Before I change the oil, it will raise above 5) Oil level gage is above the half when idle and hot.
I don't have this problem when I bought the car at early April, the oil pressure and idle were both very stable that time, and this happened the first time in the begining of May, and I have the oil changed at May 3.
Will this require an engine rebuild? Or should I change back to thicker oil, like previous owner's 10W-60?
Thanks!
My idle rpm is slightly above the third line of tachometer (the line below "1"), and I assume it's around 700~800rpm. The oil pressure is slightly below the "1" when engine is hot (temp gage above 8 o'clock line).
Most of the time idle and oil pressure are pretty stable, but sometimes they will drop a little bit then come back again. At full throttle, oil pressure will go up to around 5, but not over 5. (Before I change the oil, it will raise above 5) Oil level gage is above the half when idle and hot.
I don't have this problem when I bought the car at early April, the oil pressure and idle were both very stable that time, and this happened the first time in the begining of May, and I have the oil changed at May 3.
Will this require an engine rebuild? Or should I change back to thicker oil, like previous owner's 10W-60?
Thanks!
05-15-2004, 12:48 PM
#5
Intermediate
Join Date: May 2003
Location: Oxfordshire, Uk
Posts: 41
Likes: 0
Received 0 Likes
on
0 Posts
Hi,
I too used to have a problem with oil light ocasionally coming on when engine normal op temp , I have same oil as you
My idle used to dip to around 400- 500rpm then settle at 800- 900 after a second or so, but this caused the oil light to come on and would take about 5 seconds to go out
I fixed the idle problem and since then no oil light oil, pressure just over 1 at idle
cheers
Richard
I too used to have a problem with oil light ocasionally coming on when engine normal op temp , I have same oil as you
My idle used to dip to around 400- 500rpm then settle at 800- 900 after a second or so, but this caused the oil light to come on and would take about 5 seconds to go out
I fixed the idle problem and since then no oil light oil, pressure just over 1 at idle
cheers
Richard
05-15-2004, 01:53 PM
#6
Addict
Lead Rennlist
Technical Advisor
Rennlist
Lifetime Member
Lead Rennlist
Technical Advisor
Rennlist
Lifetime Member
Dear Patrick,
Going to a thicker oil will not help. In fact it may have masked the problem at the point of sale.
I have given you my recommendations and I believe you should look at the problem yourself or have it looked at.
It would seem to me by your data that you may well have a tired engine. I believe your oil pressure is too low. This could be an idle issue as already stated.
You are stalling which means there is a problem somewhere. A vacuum leak may cause such a situation so a visual inspection of all vacuum lines and systems might be in order. I am sorry but from here on in you ar elooking at needing to get your hands dirty and start doing some troubleshooting.
Ciao,
Adrian
964C4
Going to a thicker oil will not help. In fact it may have masked the problem at the point of sale.
I have given you my recommendations and I believe you should look at the problem yourself or have it looked at.
It would seem to me by your data that you may well have a tired engine. I believe your oil pressure is too low. This could be an idle issue as already stated.
You are stalling which means there is a problem somewhere. A vacuum leak may cause such a situation so a visual inspection of all vacuum lines and systems might be in order. I am sorry but from here on in you ar elooking at needing to get your hands dirty and start doing some troubleshooting.
Ciao,
Adrian
964C4
Trending Topics
11-20-2006, 11:02 PM
#10
Racer
Join Date: Jan 2003
Location: Hong Kong
Posts: 289
Likes: 0
Received 0 Likes
on
0 Posts
Hi!
I had the similar problem except that the oil temp was rather high, reaching near 10/11 o'clock but still not in red. It turned out to be the fault resiostor which turn the oil cooling fan on at low speed rather than high speed. I changed the resistor and it is now fine.
Eddy
I had the similar problem except that the oil temp was rather high, reaching near 10/11 o'clock but still not in red. It turned out to be the fault resiostor which turn the oil cooling fan on at low speed rather than high speed. I changed the resistor and it is now fine.
Eddy
